petmoosie: (braids)
petmoosie ([personal profile] petmoosie) wrote2009-07-12 07:24 pm
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OK, math geek

"
an infinite number of peptide hormones involved in the digestive system

The Math Geek Says: That's not possible. There'd have to be no upper bound on the number of atoms in the hormone. In a person who weighs, say, 100 kg, there are no more than 6.022*1028 atoms (that's the number if they were all hydrogen atoms); and there can't be more atoms in the hormone than there are in the entire body.

Now, granted, the only upper bound I can place on the number of hormones (without knowing more about their structure) is (6.022*1028)!, which certainly qualifies as Lots. But it's still finite. :-)" from [livejournal.com profile] metageek 's comment at least a year ago.

Possible hormones in the digestive system are peptide hormones so they are composed of any of 20 amino acids, in a chain of length 3 to 30 amino acids long. So a mathematical expression for that would be:

20^3 +20^4 +20^5 + ... + 20^30, where the ... is terms of 20^n for n=6 to 29.  Is there any compact way to express this? Is there a way of doing this in a shorter way?
 

Re: Yes, and yes

[identity profile] metageek.livejournal.com 2009-07-13 12:21 pm (UTC)(link)
How did you get the summation sign? and the subscripts/superscripts to appear?

Summation is just &sum; (see Character entity references in HTML 4, from the HTML spec); (sub|super)scripts are <sub> and <sup>, respectively.